Continuous free layer spin valve sensor with patterned exchange underlayer stabilization

ABSTRACT

A spin valve device comprises a free layer, a spacer layer, a pinned layer, an antiferromagnetic layer, and a patterned underlayer that includes a magnetic material for providing trackwidth and longitudinal bias. The patterned underlayer can comprise a buffer layer, an antiferromagnetic layer and a ferromagnetic layer. Alternatively, the patterned underlayer can comprises a buffer layer, a chromium layer and a hard biasing, permanent magnetic layer which provides trackwidth and longitudinal bias. A lower conductor can be located on the underlayer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to magnetoresistive (MR) sensors and moreparticularly to MR sensor devices and methods of fabrication thereof.

2. Description of Related Art

Kim et al., U.S. Pat. No. 5,608,593 for “Shaped Spin Valve TypeMagnetoresistive Transducer and Method for Fabricating the SameIncorporating Domain Stabilization Technique” shows a spin valve (SV)with a permanent magnet with a non-magnetic (e.g., Cr) underlayer(Separation layer). (See col. 5, lines 15 to 25.)

Ravipati, U.S. Pat. No. 5,709,358 for a “Spin Valve MagnetoresistiveTransducers Having Permanent Magnets” has thin film layers offerromagnetic material separated from each other by a nonmagneticspacer. The direction of magnetization of one thin ferromagnetic layersis pinned by a permanent magnetic layer. Another permanent magneticlayer is located adjacent to the other thin film layer to providelongitudinal biasing.

Mauri, U.S. Pat. No. 5,796,561 for a “Self-biased Spin Valve Sensor”discloses a Spin Valve (SV) MagnetoResistive (MR) sensor with a freelayer separated from a pinned layer by a spacer layer.

Takada et al., U.S. Pat. No. 5,828,527 for a “Thin Film Magnetic HeadHaving Magnetic Resistance Effect Stabilizing Layer” describes a thinfilm magnetic head with a magnetoresistance effect stabilizing layerwith an underlayer of Ta or oxides of Al or Si, a buffer layer ofchromium (Cr), a separation layer of Cr or Ta and a hard magnetic layer.

SUMMARY OF THE INVENTION

A spin valve device comprises a free layer, a spacer layer, a pinnedlayer, an antiferromagnetic layer, and a patterned underlayer thatincludes a magnetic material for providing trackwidth and longitudinalbias. The patterned underlayer can comprises a buffer layer, anantiferromagnetic layer and a ferromagnetic layer. Alternatively, thepatterned underlayer can comprises a buffer layer, a chromium layer anda magnetically hard, i.e. permanently magnetic, layer which providestrackwidth, longitudinal bias, and magnetic stabilization.

In accordance with this invention a continuous fee layer spin valve (SV)Sensor with a patterned exchange underlayer stabilization. Theunderlayer (antiferromagnet) is formed under the magnetically hard orpermanently magnetic (PM) material.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other aspects and advantages of this invention areexplained and described below with reference to the accompanyingdrawings, in which:

FIG. 1 illustrates a technique using an abutted junction with asputtered permanent magnet.

FIG. 2 shows an embodiment in accordance with this invention eliminatingthe uncertainty of taper properties by using a continuous free layerapproach.

FIGS. 3A-3E show the process steps for forming a second embodiment ofthe device of FIG. 2.

FIGS. 4A-4E show the process steps for forming a third embodiment of thedevice of FIG. 2.

FIGS. 5A-5E show the process steps for forming a fourth embodiment ofthe device of FIG. 2.

FIGS. 6A-6E show the process steps for forming a fifth embodiment of thedevice of FIG. 2.

FIG. 7 shows an alternative embodiment of this invention which is amodification of the device of FIG. 1 with replacement of the permanentmagnet layer PM and underlayer UL with a perpendicularly oriented,permanently magnetic (hard magnetic) layer PM′.

In FIG. 8, the first conductor layer of FIGS. 3E and FIG. 4E waseliminated so that the first antiferromagnetic layer is formed directlyon the buffer layer eliminating the second layer formed above the gapmaterial.

In FIG. 9, the first conductor layer of FIGS. 3E and FIG. 4E has beenreplaced by a thin, ferromagnetic layer FM formed directly on the bufferlayer L1 to promote growth.

In FIG. 10, the first conductor layer of FIGS. 5E and 6E was eliminatedso that the underlayer is formed directly on the buffer layer,eliminating the first conductor layer.

In FIG. 11, the first conductor layer C1 of FIGS. 5E and FIG. 6E wasreplaced by a thin, ferromagnetic layer FM formed directly on the bufferlayer L1 to promote growth.

DESCRIPTION OF THE PREFERRED EMBODIMENT

One of major challenges of spin valve (SV) and AMR magnetic recordinghead is the problem of domain stabilization. One technique is to use anabutted junction with sputtered permanent magnet (PM), as illustrated byFIG. 1. The device of FIG. 1 includes a gap layer G1, a buffer layer BL,a pair of FerroMagnetic (FM) free layers FLA, a spacer layer SP, aFerroMagnetic (FM) pinned layer PIL, an AntiFerroMagnetic layer AFM, anda tantalum (Ta) Cap Layer CL in a stack.

On the right side of the stack there is a trench TR which has beenfilled with permanent magnet PM which provides a hard biasing function.Trench TR has a tapered sidewall extending down through the layersincluding Cap Layer CL, AntiFerroMagnetic layer AFM, pinned layer PIL,spacer layer SP, free layers FLA, and buffer layer BL to the surface ofthe gap layer G1.

In the trench, a set of layers is formed partially overlapping the rightedge of the surface of the Cap Layer CL starting with an underlayer ULfor the next layer which is a hard biasing, permanent magnet layer PM,which in turn is covered by a conductor C. The problem with this designis the uncertain magnetic and structural properties of the taperedregion TPR near the junction between the stack ST and the underlayer ULand the hard biasing permanent magnet PM, and conductor C. Great effortsare needed for optimizing the stencil profiles, height and undercut, ionmilling angle and depth, deposition conditions of the hard biasing,permanent magnet layer PM and its underlayer to obtain stable devices.

First Embodiment

FIG. 2 shows an embodiment in accordance with this invention eliminatingthe uncertainty of taper properties by using a continuous free layerapproach. Longitudinal biasing is provided by exchange coupling of atail region free layer FL to patterned exchange underlayers L1-L4.

In the case of the embodiments of this invention shown in FIGS. 3A-3Eand FIGS. 4A-4E, the layers L1-L4 of FIG. 2 are as follows:

Layer L1

The bottom, buffer layer L1 is a composed of a material such as a thinrefractory metal layer, preferably tantalum, which can promote a verystrong (111) texture of the free layer FL which is mostly composed ofNiFe. Alternative refractory metals for buffer layer L1 are Nb, Ta, Ti,Zr, Hf, Mo, and W.

The underlayer L1, has three additional purposes:

1) to provide a milling stop layer,

2) to confine the redeposition to be metal during ion milling,

3) to provide a proper seed layer for SV.

At the active region, the remaining portion of buffer layer L1(tantalum, etc.) serves as a buffer layer to promote proper filmstructure (very strong (111)texture of the free layer, mostly NiFe) in aspin valve SV to obtain a high value of the change in the resistivityratio which follows: $\frac{{delta}\quad {rho}}{rho},$

where rho represents resistivity,

Layer L2

The second layer L2 is optional and comprises a conductor C1 which isincluded in some cases to reduce lead resistance. The material isselected from the group consisting of Au, Ag, W, Mo, Rh, Ru, Ti, β-Ta,TiW, TaW, and Cu₅₀Au₅₀.

In the case of the embodiments of FIGS. 5A-5E and FIGS. 6A-6E thematerial is selected from the above group plus the group consisting ofAg, Ti, TiW, and TaW.

Layer L3

The third layer L3 is either a first AntiFerroMagnetic layer AFM1 in theembodiments of FIGS. 3A-3E and FIGS. 4A-4E, or a chromium layer CR inthe embodiments of FIGS. 5A-5E and FIGS. 6A-6E.

Layer L3 is a first AntiFerroMagnetic layer AFM1 in the embodiments ofFIGS. 3A-3E and FIGS. 4A-4E is selected from three groups consisting ofas follows:

(A) IrMn, RhMn, RuMn, RuRhMn, FeMn, FeMnRh, FeMnCr, CrPtMn, TbCo,

(B) NiMn, PtMn, PtPdMn, and

(C) NiO, CoO, CoNiO.

Layer L3 is a chromium (Cr) layer preferably with a thickness of 50 Å inthe embodiments of FIGS. 5A-5E and FIGS. 6A-6E.

Layer L4

Layer L4 is a thin ferromagnetic, NiFe layer TFM in the embodiments ofFIGS. 3A-3E and FIGS. 4A-4E or layer L4 is a hard biasing, permanentmagnetic layer PM in the embodiments of FIGS. 5A-5E and FIGS. 6A-6E.

For FIGS. 3A-3E and FIGS. 4A-4E, during the deposition of the L4 (FM)and SV stack thereabove, the layer L4 with layer L3 Group (A) and (C)AFM1 materials of an alignment field is required and a field annealingat later process step after SV is completed to set the pinning directionof AFM1 longitudinally. For Group (B) AFM material, a field annealing atsome specified angle and higher temperature is needed between processstep 1 and 2 to get final pinning direction of AFM1 to be longitudinal.The final configuration is shown in FIG. 2.

The second embodiment of the invention of FIG. 2 is shown by FIGS.3A-3E, which includes the process steps as follows:

1. Referring to FIG. 3A, a device 30 includes an aluminum oxide (Al₂O₃)gap layer G1. On the surface of gap layer G1 are deposited blanketlayers of a refractory, buffer layer L1, a conductor layer C1, anantiferromagnetic (L3) layer AFM1 and a thin ferromagnetic (NiFe) layerL4. Layers L1, C1, AFM1 and L4 are deposited with the compositionsdefined above. On top of antiferromagnetic (L3) layer AFM1, a thinferromagnetic layer (L4) can be sputtered at the same to increase thelongitudinal biasing strength. The ferromagnetic layer (L4) is stronglycoupled to AFM1 layer L3 and is optional.

2. Referring to FIG. 3B, the device 30 of FIG. 3A is shown a photoresistlayer PR was spun onto the top of layer TFM on top of device 30, andphotoresist layer PR was patterned and developed with a window W with atrack width TW.

3. Next ion milling with ions IM is performed to mill through layersTFM/AFM1/C1 (L4/L3/L2).

4. Referring to FIG. 3C, the device 30 of FIG. 3B is shown after the ionmilling continued to form a tapered window W! in the photoresist PRwhich has been milled to a thinner layer PR! with a wider opening, andbelow the window W! extends an inwardly tapered depression D through thethin ferromagnetic (NiFe) layer L4, antiferromagnetic (L3) layer AFM1and the conductor layer C1, stopping in the middle of layer L1 with thelayer L1 serving as an ion milling stop layer forming the bottom of thewindow W!.

5. Referring to FIG. 3D, the device 30 of FIG. 3C is shown after theremaining photoresist PR′ was stripped and the full spin valve stack SVhas been deposited. After sputter etching the surface of L1 was cleanedat the active region in window W′ and the surface of layer TFM (L4) wascleaned or the surface of layer AFM1 (L3) was cleaned at the tailregion. At the tail region, the free layer is strongly coupled to layerTFM (L4) or layer AFM1 (L3), providing longitudinal stabilization whicheliminates side reading. The process steps leading to the product seenin FIG. 3E.

6. Form a blanket free layer FL (NiFe, CoFe, etc.) over the layer TFM.The free layer FL is strongly exchange coupled to the firstantiferromagnetic layer AFM1 to diminish side reading of the sensor andprovide longitudinal biasing.

7. Form a blanket copper (Cu) layer CU over the free layer FL.

8. Form a pinned layer PIL over the blanket copper (Cu) layer CU

9. Form a second antiferromagnetic layer AFM2 composed of PtMn, PtPdMn,IrMn, etc. over the pinned layer PIL.

The group of materials for antiferromagnetic (L3) layer AFM1 are thesame materials as the materials for the second antiferromagnetic layerAFM2, i.e. materials selected from the group consisting of PtMn, PtPdMn,IrMn, and so forth.

For the Group (A) and (C) AFM material, an alignment field is requiredduring deposition of layer FM (L4) and a spin valve stack SV, and afield annealing at later process step after spin valve stack SV iscompleted to set the pinning direction of AFM1 longitudinally.

For Group (B) AFM material, a field annealing at some specified angleand higher temperature is needed between process step 1 and 2 to get thefinal pinning direction of AFM1 to be longitudinal.

10. Referring to FIG. 3E, the device 30 of FIG. 3D is shown in the formof a preferred embodiment of this invention. A patterned conductor C2 isformed aside from the track width TW, leaving the head exposed betweenthe portions of conductor C2 on the sides in order to reduce total leadresistance. The additional conductor layer C2 is deposited with aliftoff process using a photoresist stencil that is aligned to thetrackwidth TW defining pattern using a process similar to what is shownin FIGS. 4A-4C below, as will be well understood by those skilled in theart. Conductor layer C2 is especially needed in cases in which there isno C1 conductor layer.

In the case of NiMn, PtMn, PtPdMn as layer AFM1, field annealingperformed at high temperature and some specified angle is required toform longitudinal biassing of the tail region, after all the annealingof the SV is done, (the layer AFM2 is annealed in the HA direction.) Inthe case of IrMn, etc. serious low temperature magnetic setting may beneeded at a later stage to properly set the longitudinal biassingdirection.

An alternative process to create a device 30 with an exchange underlayeris by using a lift off process as illustrated by FIGS. 4A-4E.

1. FIG. 4A shows the alternative device 30 after depositing therefractory metal (Ta) layer L1 in an initial stage of manufacture.

2. In FIG. 4B, the device 30 of FIG. 4A is shown after a photoresiststencil stack has been formed. The stencil stack includes a bottomportion PRB with width TW and upper stencil PRT with a greater widththan TW developed. Then the next (L2/L3/L4) layers C1/AFM1/TFM aresputtered aside from the bottom portion PRB.

3. In FIG. 4C, the device 30 of FIG. 4B is shown after the photoresiststencil PR was lifted off to leave the depression D with correct activeregion dimension.

4. In FIG. 4D, the device 30 of FIG. 4C is shown after the whole spinvalve stack SV was deposited as described in the previous embodiment.

5. Referring to FIG. 4E, the device 30 of FIG. 4D is shown after apatterned conductor C2 was formed aside from the track width TW, leavingthe head exposed between the portions of conductor C2 on the sides inorder to reduce total lead resistance. The additional conductor layer C2is deposited with a liftoff process using a photoresist stencil that isaligned to the trackwidth TW defining pattern using a process similar towhat is shown in FIGS. 4A-4C above, as will be well understood by thoseskilled in the art. Conductor layer C2 is especially needed in cases inwhich there is no C1 conductor layer.

Advantages of Second and Third Embodiments

The advantages of the second embodiment of the invention of FIG. 2 seenin FIG. 3E and the third embodiment of the invention of FIG. 2 seen inFIG. 4E are as follows:

1. The free layer FL is continuous. The sensor region is longitudinalwith biasing regions which are made of the same material and there is nodisruption in magnetic and physical properties between them unlikeabutted junction design of FIG. 1 (no tapered region).

2. The same material like IrMn can be made very thin 50 Å about 80 Å tohave very high exchange. Then the shadowing effect of the ion millingprocess can be minimized.

3. Except for the sensor region, all the rest of the free layer isstrongly coupled to the AFM1 layer to make it capable of not beingresponsive to external fields and providing a robust recording head.

Modifications of Second and Third Embodiments

Referring to FIG. 8, the first conductor layer C1 of FIGS. 3E and FIG.4E was eliminated and the first antiferromagnetic layer AFM1 was formeddirectly on the buffer layer L1, eliminating first conductor layer C1(i.e. the second layer L2) formed on the gap material G1.

Referring to FIG. 9, the first conductor layer C1 of FIGS. 3E and FIG.4E was replaced by a thin, ferromagnetic layer FM formed directly on thebuffer layer L1 to promote growth.

Fourth Embodiment

In the fourth embodiment of the device of FIG. 2 shown in FIGS. 5A-5E,the process steps are the same as for FIGS. 3A-3E except that layer L3is a chromium layer CR and layer L4 is a hard biasing, permanentmagnetic layer PM as described above.

In this embodiment the uncertainty of taper properties is againeliminated by using the continuous free layer approach. The longitudinalbiasing is provided by a hard biasing, permanent magnet (PM) underlayerthat is deposited as a full film with well controlled film properties.The process steps are listed in the attached notes. At the first step, athin refractory metal underlayer (L1), an optional conductor layer C1(L2), and chromium underlayer CR (L3) for layer PM (L4) are deposited asfull, blanket films. Then in FIG. 5B, a photoresist layer PR is spun on,exposed to a patterning mask and developed with the correct track widthTW. Then ion milling IM is performed to mill through layers (L4/L3/L2)L1/C1/CR/PM and stop at middle of L1 forming depression D and thinningmask PR to thickness and configuration of remaining mask PR′.

Then in FIG. 5C the remaining photoresist mask PR′ is stripped. Aftersputter etch cleaning the surface of layer L1 at the active region andlayer PM (L4) at the tail region, in FIG. 5D, the full spin valve stackSV is deposited. At the active region in depression D, the remainingthickness of layer L1 serves as a buffer layer to promote proper filmstructure (very strong (111)texture of free layer, mostly NiFe) in SV toobtain high delta rho/rho. At the tail region, the free layer can beferromagnetic coupled to PM (L4) if no additional refractory bufferlayer is included in SV stack, or is simply magnetostatically coupled toPM. The PM can be either longitudinal or vertically magnetized toprovide longitudinal stabilization to the active sensor region whileeliminates side reading.

Referring to FIG. 5E, the device 30 of FIG. 5D is shown in the form of apreferred embodiment of this invention. A patterned conductor C2 isformed aside from the track width TW, leaving the head exposed betweenthe portions of conductor C2 on the sides in order to reduce total leadresistance. The additional conductor layer C2 is deposited with aliftoff process using a photoresist stencil that is aligned to thetrackwidth TW defining pattern using a process similar to what is shownin FIGS. 4A-4C above, as will be well understood by those skilled in theart. Conductor layer C2 is especially needed in cases in which there isno C1 conductor layer.

The L1 layer has three purposes: 1) to provide a milling stop layer, 2)to confine the redeposition to be metal during ion milling, 3) toprovide a proper seed layer for SV. Its material can be chosen fromrefractory metal: Nb, Ta, Ti, Zr, Hf, Mo and W.

Layer L2 is optional for reduction of lead resistance. Layer L2 can bemade of a material chosen from the following: Au, Ag, W, Mo, Rh, Ru, Ti,β-Ta, TiW, TaW, Cu₅₀Au₅₀.

Longitudinally permanent magnetic layer PM in FIGS. 5A-5E can be one ofCo, CoPt, CoSm, CoPtCr, CoCrTa, CoPtB, CoCrTaPt, and CoCrPtB.

For vertically magnetized PM, the underlayer can be omitted and itsmaterial should be one of Co, CoCr, CoSm, and Ba-ferrite.

In the TW region, the underlayer provides a good buffer layer. In thetail region, the PM exchange coupling to the free layer stiffens thetail region. The PM provides longitudinal biassing. There are nojunctions in the free layer between the active region and the tailregion. There is no taper complexity of magnetic and materialproperties.

Fifth Embodiment

An alternative process to create a device 30 with an exchange underlayeris by using a lift off process as illustrated by FIGS. 6A-6E.

1. FIG. 6A shows the alternative device 30 after depositing therefractory metal (Ta) layer L1 in an initial stage of manufacture.

2. In FIG. 6B, the device 30 of FIG. 6A is shown after a photoresiststencil stack has been formed. The stencil stack includes a bottomportion PRB with width TW and upper stencil PRT with a greater widththan TW developed. Then the next (L2/L3/L4) layers C1/CR/PM′ aresputtered aside from the bottom portion PRB.

3. In FIG. 6C, the device 30 of FIG. 6B is shown after the photoresiststencil PR was lifted off to leave the depression D with correct activeregion dimension.

4. In FIG. 6D, the device 30 of FIG. 6C is shown after whole spin valvestack SV was deposited as described in the previous embodiment.

5. In FIG. 6E, the device 30 of FIG. 6D is shown after a patternedconductor C2 is formed aside from the track width TW, leaving the headexposed between the portions of conductor C2 on the sides in order toreduce total lead resistance. The additional conductor layer C2 isdeposited with a liftoff process using a photoresist stencil that isaligned to the trackwidth TW defining pattern using a process similar towhat is shown in FIGS. 4A-4C above, as will be well understood by thoseskilled in the art. Conductor layer C2 is especially needed in cases inwhich there is no C1 conductor layer.

Advantages of Fourth and Fifth Embodiments

The advantages of the fourth and fifth embodiments of the inventionillustrated by the embodiment shown in FIG. 2 are as follows:

a) The free layer has no junctions. The magnetic and film properties arecontinuous from active sensor region to tail stabilization region.

b) The exchange underlayer (L3) and longitudinal biasing enhance layer(L4) film properties are well defined even at edges because they aredeposited as full films.

c) The magnetic free layer does not have a taper region.

d) The underlayer (L1) provides a milling stop layer to control thevariation of milling depth, and the remaining L1 in active region willserve as a buffer layer to promote good spin valve structure.

Modifications of Fourth and Fifth Embodiments

Referring to FIG. 10, the first conductor layer C1 of FIGS. 5E and 6Ewas eliminated and the chromium underlayer CR was formed directly on thebuffer layer L1, eliminating first conductor layer C1 (i.e. the secondlayer L2).

Referring to FIG. 11, the first conductor layer C1 of FIGS. 5E and FIG.6E was replaced by a thin, ferromagnetic layer FM formed directly on thebuffer layer L1 to promote growth.

Sixth Embodiment

FIG. 7 shows an alternative embodiment of this invention which is amodification of the device of FIG. 1 with replacement of the hardbiasing, permanent magnet layer PM and underlayer UL with aperpendicularly oriented hard biasing, permanent magnet layer PM′.However, the hard biasing, permanent magnet PM′ is composed of amaterial selected from the group consisting of the alloy of cobaltchromium (CoCr), the alloy of cobalt samarium (CoSm), and barium(Ba)-ferrite which has a crystallized anisotropy pointing out the filmplane to form a perpendicular hard biasing, permanent magnet.

Unlike FIG. 1, in FIG. 7 the sputtered hard biasing, permanent magnetlayer PM′ overlies the surface of a gap layer G1 and forms an abuttedjunction with a stack of layers including buffer layer BL, a pair ofFerroMagnetic (FM) free layers FLA, spacer layer SP, a FerroMagnetic(FM) pinned layer PIL, an AntiFerroMagnetic layer AFM, and a tantalum(Ta) Cap Layer CL in a stack. In other words, on the right side of thestack there is a trench TR which has been filled with hard biasing,permanent magnet PM. Trench TR has a tapered sidewall extending downthrough the layers including the Cap Layer CL, the AntiFerroMagneticlayer AFM, the pinned layer PIL, the spacer layer SP, the free layersFLA, and buffer layer BL to the surface of the gap layer G1.

In the trench, a set of layers is formed overlapping partially on theright edge of the surface of the Cap Layer CL starting with the hardbiasing, permanent magnet layer PM′, which in turn is covered by theconductor C.

Preferably, in accordance with this invention, a conductor layer edge iswider than an underlayer edge.

In addition, in accordance with this invention, a conductor layer edgeis smaller than an underlayer edge.

While this invention has been described in terms of the above specificembodiment(s), those skilled in the art will recognize that theinvention can be practiced with modifications within the spirit andscope of the appended claims, i.e. that changes can be made in form anddetail, without departing from the spirit and scope of the invention.Accordingly, all such changes come within the purview of the presentinvention and the invention encompasses the subject matter of the claimswhich follow.

What is claimed is:
 1. A spin valve device comprising: a gap layer, abuffer layer having a top surface and which is composed of a refractorymaterial formed over the gap layer, patterned underlayers formed on thebuffer layer including: a) a conductor layer formed on the buffer layer,b) a chromium layer formed on the conductor layer, c) a hard biasingpermanent magnetic layer formed on the chromium layer, an inwardlytapered depression in the patterned underlayers down to the surface ofthe buffer layer, a stack of layers formed covering the patternedunderlayers and reaching down to cover the inwardly tapered depressionincluding: d) a free layer, e) a spacer layer, f) a pinned layer, g) anupper antiferromagnetic layer, whereby the patterned underlayers, whichare located aside from the inwardly tapered depression, providetrackwidth and longitudinal bias.
 2. The device of claim 1 wherein thehard biasing, permanent magnet is longitudinally magnetized.
 3. Thedevice of claim 2 wherein the hard biasing, permanent magnet consists ofa material selected from the group of materials consisting of Co, CoPt,CoSm, CoPtCr, CoCrTa, CoPtB, CoCrTaPt, and CoCrPtB.
 4. The device ofclaim 1 wherein the conductor consists of a material selected from thegroup of materials consisting of Au, Ag, W, Mo, Rh, Ru, Ti, β-Ta, TiW,TaW, Cu₅₀Au₅₀.
 5. A spin valve device comprising: a gap layer, a bufferlayer having a top surface and which is composed of a refractorymaterial formed over the gap layer, patterned underlayers formed on thebuffer layer including: a) a conductor layer formed on the buffer layer,b) a lower antiferromagnetic layer formed on the conductor layer, c) athin ferromagnetic layer formed on the lower antifesrromagnetic layer,an inwardly tapered depression in the patterned underlayers down to thesurface of the buffer layer, a stack of layers formed covering thepatterned underlayers and reaching down to cover the inwardly tapereddepression including: d) a free layer, e) a spacer layer, f) a pinnedlayer, g) an upper antiferromagnetic layer, whereby the patternedunderlayers which are located aside from the inwardly tapered depressionprovide trackwidth and longitudinal bias.
 6. The device of claim 5wherein the lower antiferromagnetic material is selected from the groupof materials consisting of IrMn, RhMn, RuMn, RuRhMn, FeMn, FeMnRh,FeMnCr, CrPtMn, TbCo, NiMn, PtMn, PtPdMn, NiO, CoO, and CoNiO.
 7. Thedevice of claim 5 wherein the buffer layer consists of a materialselected from the group of materials consisting of Nb, Ta, Ti, Zr, Hf,Mo, W.
 8. The device of claim 5 wherein the ferromagnetic layer consistsof at least one material selected from the group of materials consistingof Co, CoFe, Ni, and NiFe.
 9. The device of claim 5 wherein a conductoris provided consisting of a material selected from the group ofmaterials consisting of Au, Ag, W, Mo, Rh, Ru, Ti,β-Ta, TiW, TaW, andCu₅₀Au₅₀.
 10. The device of claim 5 wherein a conductor layer withreduced lead resistance was added and aligned after spin valvedeposition.